Mesenchymal hamartomas of the liver may be associated with increased serum alpha foetoprotein concentrations and mimic hepatoblastomas

Mesenchymal Hamartoma With Elevated Alpha-Fetoprotein: A Diagnostic Pitfall

Mesenchymal hamartoma (MH) is a benign liver tumor accounting for 3% to 8% of all liver tumors in children, commonly manifesting before 3 years of life. Distinguishing MH from hepatoblastoma and other liver tumors relies on imaging and alpha-fetoprotein (which is usually within normal range in MH), before histologic examination. We report a case of a hepatic MH associated with elevated alpha-fetoprotein, leading to a misdiagnosis of hepatoblastoma and the administration of chemotherapy. We draw the attention to the diagnostic difficulty and pitfalls related to alpha-fetoprotein elevation in the setting of a liver tumor, and we highlight the importance of imaging and histology in establishing the diagnosis.

Giant Mesenchymal Hepatic Hamartomas With Adrenal Involvement Precipitating Respiratory Failure: A Myxomatous Mystery in a Three-Month-Old

The combination of placental mesenchymal dysplasia and hepatic mesenchymal hamartomas is an extremely rare finding. We present the case of a three-month-old female born at 35 weeks gestation with a history of placental mesenchymal dysplasia who presented with non-bilious, non-bloody emesis, and episodes of respiratory distress due to multiple enlarging abdominal cystic lesions. The patient's presentation was unique due to both liver and adrenal solid and cystic lesions. After extensive imaging and multiple biopsies, expert interpretation of biopsy tissue revealed hepatic mesenchymal hamartoma within the liver and the adrenal gland. To our knowledge, this is one of the few documented cases of unresectable hepatic mesenchymal hamartomas with adrenal involvement successfully undergoing a whole liver transplant.

Pediatric Mesenchymal Hamartomas of the Liver can Show Both Foregut and Hindgut Phenotype

Cystic epithelium in mesenchymal hamartoma (MH) is typically biliary type. Mucinous differentiation of the epithelium and increased hepatocellular component may pose a diagnostic challenge. We studied MH in 7 children (6 M, 1 F; age 4 months to 8 years, median 1 year). Resected tumors varied from 3.0 to 17.0 cm. All tumors showed biliary epithelium in the cystic component with strong and diffuse reactivity for CK7 and CK19. Expression of CK20 and CDX2 was additionally seen in 2 tumors, rare/focal in 1, and diffuse with mucinous differentiation in the other. Strong and continuous nuclear reactivity for Sox9 was seen in the cyst epithelium in all 7 tumors including focal staining in mucinous areas. It was also positive in the hepatocellular component. CD56 and vimentin were variably positive in the cystic epithelium of all cases. Alpha-fetoprotein showed patchy weak staining in the hepatocellular component and was negative in the cystic epithelium. Hepar-1 showed focal staining in the cystic epithelium in 4/7 cases and diffuse in the hepatocellular component. Both patients showing CK20 and CDX2 expression had abnormal chromosomal analysis: one with balanced translocation between chromosomes 2 and 19 and other with loss of chromosome Y. Among others, one showed 46,XY,inv(9)(p11q12), one did not grow cells, and the remaining 3 had normal karyotype. Six patients underwent resection and one had liver transplantation. All were alive and well with a median follow-up of 1.5 years. In conclusion, mucinous epithelium can be seen in MH. Expression of Sox9 in the cyst epithelium and hepatocytes suggests a common origin for these components. Expression of vimentin indicates an overlapping epithelial-mesenchymal phenotype. Hepatic MH can show divergent epithelial differentiation including both foregut and hindgut phenotype, which may provide insights into the pathogenesis of this rare neoplasm but does not seem to affect the outcome in this limited series.

Mesenchymal hamartoma mimicking hepatoblastoma: A cytological pitfall

The case of a 9-month-old infant who presented with an abdominal mass since birth is discussed here. Fine-needle aspiration (FNA) cytology of this mass was performed, from which it was thought to be a small round tumor, possibly a hepatoblastoma (HB). Histopathologically, however, it was found to be a mesenchymal hamartoma (MH). This case report thus highlights this cytological limitation.

Benign liver tumors in pediatric patients - Review with emphasis on imaging features

Benign hepatic tumors are commonly observed in adults, but rarely reported in children. The reasons for this remain speculative and the exact data concerning the incidence of these lesions are lacking. Benign hepatic tumors represent a diverse group of epithelial and mesenchymal tumors. In pediatric patients, most benign focal liver lesions are inborn and may grow like the rest of the body. Knowledge of pediatric liver diseases and their imaging appearances is essential in order to make an appropriate differential diagnosis. Selection of the appropriate imaging test is challenging, since it depends on a number of age-related factors. This paper will discuss the most frequently encountered benign liver tumors in children (infantile hepatic hemangioendothelioma, mesenchymal hamartoma, focal nodular hyperplasia, nodular regenerative hyperplasia, and hepatocellular adenoma), as well as a comparison to the current knowledge regarding such tumors in adult patients. The current emphasis is on imaging features, which are helpful not only for the initial diagnosis, but also for pre- and post-treatment evaluation and follow-up. In addition, future perspectives of contrast-enhanced ultrasound (CEUS) in pediatric patients are highlighted, with descriptions of enhancement patterns for each lesion being discussed. The role of advanced imaging tests such as CEUS and magnetic resonance imaging, which allow for non-invasive assessment of liver tumors, is of utmost importance in pediatric patients, especially when repeated imaging tests are needed and radiation exposure should be avoided.

Aberrant expression of cancer stem cell markers (CD44, CD90, and CD133) contributes to disease progression and reduced survival in hepatoblastoma patients: 4-year survival data

Hepatoblastoma (HB) is an embryonal tumor of the liver in children. Prognosis and response to treatment in HB are highly variable. Cancer stem cells (CSCs) constitute a population of cells, which contribute to the development and progression of many tumors. However, their role in HB is not well defined yet. We assessed the prognostic and predictive values of some CSC markers in HB patients. Protein and messenger RNA expressions of the CSC markers CD133, CD90, and CD44 were assessed in 43 HB patients and 20 normal hepatic tissues using immunohistochemistry and quantitative real-time polymerase chain reaction. The expression levels of these markers were correlated to standard prognostic factors, patients' response to treatment, overall survival (OS), and disease-free survival (DFS). CD44, CD90, and CD133 proteins were detected in 48.8%, 32.6%, and 48.8% compared with 46.5%, 41.7%, and 58.1% RNA, respectively (concordance, 77.8%-96%). None of the normal tissue samples was positive for any of the markers. Significant correlations were reported between α-fetoprotein and both CD44 and CD133 (P = 0.02) as well as between tumor types CD90 and CD133 (P = 0.009). Reduced OS correlated with CD44, CD90, and CD133 expressions (P < 0.001), advanced stage (P < 0.001), response to treatment (P < 0.001), and total excision of the tumor. Reduced DFS correlated with CD44 and CD133 expressions (P < 0.001) only. In conclusion, CD133, CD44, and CD90 could be used as prognostic and predictive markers in HB. High expression of these markers is significantly associated with poor response to treatment and reduced survival. Moreover, complete surgical resection and systemic chemotherapy are essential to achieve good response and prolonged survival, especially in early stage patients.

Renal and hepatic tumors in the neonatal period

Renal and hepatic tumors in neonates are extremely rare. Nevertheless it is important for clinicians to be familiar with them. Both renal and hepatic neonatal tumors are heterogeneous collections of several tumor types. Some renal and hepatic tumors are benign and may require no interventions whereas others can be associated with significant morbidity and even mortality and may require multimodality treatment. Early diagnosis and initiation of the proper treatment plan is crucial for achieving the best outcomes for these rare tumors in this vulnerable population.

[Paediatric malignant liver tumours]

Tumours and pseudotumours of the liver are a heterogeneous group of neoplasm including 60% of malignant tumours. Malignant liver tumours account for less than 2% of the lesions in children and vary considerably in incidence throughout the paediatric age range, with hepatoblastoma, rhabdoid tumour of the liver, hemangioendothelioma, biliary tract rhabdomysosarcoma and mesenchymal hamartoma in the first two years of life and hepatocellular carcinoma, focal nodular hyperplasia, and undifferentiated sarcoma in older children and adolescents. Treatment of malignant epithelial tumours is based on the surgical resection of the tumour associated with pre- and postoperative chemotherapy including cisplatinum. Modalities of the treatment are adapted to risk factors. Survival rates at three years are over 80% for localised hepatoblastoma whereas they are less than 30% in hepatocellular carcinomas. The role of targeted therapies still has to be defined.

Expression of glypican-3 in undifferentiated embryonal sarcoma and mesenchymal hamartoma of the liver

Glypican-3 (GPC3) is an oncofetal protein that has been demonstrated to be a useful diagnostic immunomarker for hepatocellular carcinoma and hepatoblastoma. Its expression in mesenchymal tumors of the liver, particularly undifferentiated embryonal sarcoma (UES) and mesenchymal hamartoma (MH), has not been investigated. In this study, a total of 24 UESs and 18 MHs were immunohistochemically stained for GPC3 expression. The results showed cytoplasmic staining for GPC3 in 14 (58%) UESs, of which 6 exhibited diffuse immunoreactivity and the remaining 8 showed focal positivity. The patients with GPC3-positive UES tended to be younger (mean 18 years; median 11 years) than those with GPC3-negative tumors (mean 39.4 years; median 27 years), although the difference did not reach statistical significance (P = .06). Eight MHs also exhibited GPC3 immunoreactivity (44%; 4 diffuse and 4 focal). Positive staining in all 8 cases was primarily seen in entrapped nonlesional hepatocytes with a canalicular and cytoplasmic staining pattern. In only 4 cases (22%) was GPC3 immunoreactivity also observed in the mesenchymal component. The patients with positive staining also tended to be younger (mean 2.6 years; median 1.1 years) compared with those with negative staining (mean 16.3 years; median 4.5 years), but the difference was not statistically significant (P = .15). Our data demonstrate that GPC3 is expressed in a subset of UES and MH of the liver. Caution should thus be exercised when evaluating a GPC3-expressing hepatic neoplasm, particularly on a needle biopsy when the differential diagnosis includes poorly differentiated hepatocellular carcinoma or hepatoblastoma.

From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation part 1. Benign tumors

Benign hepatic tumors in children include lesions that are unique to the pediatric age group and others that are more common in adults. Infantile hemangioendothelioma, or infantile hepatic hemangioma, is a benign vascular tumor that may cause serious clinical complications. It is composed of vascular channels lined by endothelial cells. At imaging, large feeding arteries and draining veins and early, intense, peripheral nodular enhancement with centripetal filling on delayed images are characteristic features. Mesenchymal hamartoma of the liver occurs in young children and is characterized pathologically by mesenchymal proliferation with fluid-containing cysts of varying size and number. The mesenchymal component or cystic component may predominate; this predominance determines the imaging appearance of the tumor. Benign epithelial tumors that are common in adults may infrequently occur in childhood. These include focal nodular hyperplasia (FNH), hepatocellular adenoma, and nodular regenerative hyperplasia. All are composed of hyperplastic hepatocytes similar to surrounding liver parenchyma and may be difficult to discern at imaging. Preferential hepatic arterial phase enhancement helps distinguish FNH and hepatic adenoma from uninvolved liver. Hepatic adenoma often has intracellular fat and a propensity for intratumoral hemorrhage, neither of which are seen in FNH. Unlike adenoma, FNH often contains enough Kupffer cells to show uptake at sulfur colloid scintigraphy. Nodular regenerative hyperplasia is often associated with portal hypertension, which may be evident at imaging. Knowledge of how the pathologic features of these tumors affect their imaging appearances helps radiologists offer an appropriate differential diagnosis and management plan.

[Mesenchymal hamartoma of the liver in a child: a case report]

Mesenchymal hamartoma of the liver is a rare, benign tumor that presents mostly before the age of 2 years. Its pathogenesis is poorly understood. We present the case of a 2.5-year-old female patient who had a large cystic mass of the liver of which the hamartomatous nature was confirmed by the pathological examination of the surgical specimen. We discuss the clinicopathological, imaging, and histological features of this unusual tumor through a review of the literature.

Difficulties in the management of mesenchymal hamartomas

AIM

Mesenchymal hamartoma of the liver is an entity with a varied presentation and frequent initial delay in diagnosis. The macroscopic appearance too is quite heterogeneous with solid, cystic and mixed variants being present with varying degrees of vascularity. Management will depend on presentation and expertise available. We look at a single centre experience with the mesenchymal hamartomas.

METHOD

Retrospective patient record review of the past 30 years, 1976-2006.

RESULTS

Seventeen patients aged 1 day to 15 years were identified, with a histopathological diagnosis of mesenchymal hamartoma of the liver. The anatomical location in the liver was 12 in the right liver and the 5 in the left. All patients presented with abdominal distension, eight had significant anorexia and or vomiting. Ultrasound scan was done in all patients. Findings were that of a mass and or cysts. The cysts were multiple in all cases but one and were interspersed with solid elements. Calcification was noted in only two of the patients. Operative approaches were six right hepatectomy, four wedge excision, seven tumour excisions by division of its pedicle; two of these were done laparoscopically, by cyst drainage and excision of the solid component. The tumours were all confirmed as mesenchymal hamartomas; size ranged from 412 to 2,230 g. Complications included three related to misdiagnosis (hydatid disease, and hepatoblastoma). Intraoperative problems consisted of preoperative bleeding resulting in an on-table hypovolaemic arrest and in a second case a bile duct injury. Postoperative problems consisted of an initial incomplete resection, with residual tumour on the IVC. There was rapid regrowth of tumour and death after a second exploration. Two children developed fluid collections requiring re-exploration and drainage. The surviving children have been followed up for a median time period of 4 months (range 1 month-11 years) and are well.

CONCLUSION

Although hamartomas of the liver are histologically benign, their clinical course and the complications of surgical treatment can be significant. They can often pose diagnostic dilemmas and may have a propensity for local recurrence and malignant degeneration.

Stromal-predominant mesenchymal hamartoma of the liver with elevated serum alpha-fetoprotein level

Mesenchymal hamartoma of the liver (MHL) is an uncommon, benign, tumor-like lesion and is usually diagnosed in the first 2 years of life. Its pathogenesis remains unclear. Treatment of choice is radical excision. The authors report a case of solid stromal predominant MHL in a 12-month-old male infant who also had an elevated serum alpha-fetoprotein level. He also had hypospadias, which might represent a spectrum of developmental anomalies. It usually presents as an asymptomatic mass, however, as in the reported case, it may cause several complications due to the compression of surrounding structures. He was successfully treated with total excision of the pedunculated large tumor without any complication.

Mesenchymal hamartoma of the liver mimicking hepatoblastoma

Mesenchymal hamartoma of the liver is a cystic benign liver mass occurring in children. Diagnostic confusion with hepatoblastoma may arise when alpha-feto-protein (AFP) level is elevated. We report an extremely rare case of mesenchymal hamartoma in an 11-month-old boy. Serum AFP was elevated and fine-needle aspiration biopsy suggested the lesion as hepatoblastoma, so he received preoperative chemotherapy. At the end of the preoperative chemotherapy, the tumor size and AFP level decreased. A right hepatectomy was performed. The pathologic examination of the specimen revealed mesenchymal hamartoma. Mesenchymal hamartoma of the liver with increased serum AFP levels may mimic hepatoblastoma if a cytological examination samples only the hepatocellular component of mesenchymal hamartoma. According to our knowledge, this is the first case of the mesenchymal hamartoma of the liver, which showed reduction in serum levels of AFP and involution of the tumor size by preoperative chemotherapy.

Mesenchymal hamartoma of the liver accompanied by a daughter nodule: report of a case

Mesenchymal hamartoma of the liver (MHL) is an uncommon benign tumor found primarily in children younger than 2 years of age. We report a rare case of MHL with a daughter nodule and atypical histological findings in a 14-month-old girl. On admission, computed tomography, magnetic resonance imaging, and angiography showed a solid hypovascular mass with a central cystic area in the liver. Laparotomy revealed a tumor, 8 cm in size, occupying segment 5 and parts of segments 4 and 6 of the liver, and a small nodule, 10 mm in size, in segment 7. Thus, we performed a partial hepatic resection (S4-6) and tumor extirpation (S7). The histological findings of both tumors were the same, but atypical of MHL. Recent studies on the pathogenesis of this tumor have found neoplastic features such as genetic anomalies and malignant transformation. These findings suggest that the conventional approach of completely resecting the tumor whenever possible is the best treatment.

Mesenchymal hamartoma of the liver associated with features of Beckwith-Wiedemann syndrome and high serum alpha-fetoprotein levels

A 5-month-old girl with clinical features of Beckwith-Wiedemann syndrome (BWS), including a repaired omphalocele, an earlobe crease, enlarged adrenal glands, renal size discrepancy, and hyperinsulinemic hyperglycemia, presented with a 1.9-cm liver nodule. Markedly increased serum alpha-fetoprotein (AFP) levels (1,060,000 mg/L), highly suspicious for hepatoblastoma, were detected, and resection of the liver mass was performed. Histologic sections showed features characteristic of a mesenchymal hamartoma of the liver (MHL). No features of embryonal or fetal hepatocellular proliferation or heterologous stromal components were noted. By immunohistochemistry, the hepatocytes expressed AFP, but no nuclear accumulation of beta-catenin was present. Electron microscopy revealed normal, mature hepatocytes. Here we address the diagnostic challenge of the uncommon association of MHL and BWS in the setting of markedly elevated serum AFP levels. In addition, we analyze the unusual pancreatic lesion (focal endocrine adenomatosis) leading to severe hyperinsulinemic hypoglycemia in a patient with possible BWS. We emphasize that MHLs may present with markedly increased serum AFP levels, mimicking hepatoblastomas, and may also be part of the expanding spectrum of findings of BWS.

Mesenchymal Hamartoma of the Liver With an Interstitial Deletion Involving Chromosome Band 19q13.4: A Theory as to Pathogenesis?

Mesenchymal hamartoma of the liver is the third most common liver tumor of infancy. The lesion is primarily mesenchymal in origin, believed to arise from a developmental abnormality in the formation of ductal plates during late embryogenesis. Several studies have revealed a recurrent translocation in mesenchymal hamartomas, all involving a breakpoint at chromosome band 19q13.4. We present a case with a deletion involving this locus. A 10-month-old girl presented with an asymptomatic abdominal mass. The 21.0-cm tumor arose from the surface of the liver. The cut surfaces displayed multiple cysts with intervening loose fibrous tissue. Microscopically, the tumor was mostly composed of edematous connective tissue with intervening cysts, islands of hepatocytes, and haphazard branching bile ducts. Cytogenetic analysis revealed an interstitial deletion on the long arm of chromosome 19(q13.1q13.4). The patient was discharged on postoperative day 4 without complications. The cytogenetic findings support the involvement of an alteration of a gene at chromosome band 19q13.4 in the pathogenesis of mesenchymal hamartoma of the liver.

Unresectable multifocal hepatoblastoma with cardiac extension: excellent response with HB-94 chemotherapy protocol

A 10-month-old white infant presented with abdominal distention and bilateral scrotal hernia. Imaging studies of the abdomen and thorax showed a huge liver with multiple tumor masses and calcification involving all the segments. There was thrombosis in the inferior vena cava and right atrium. alpha-Fetoprotein was 246,000 IU/mL. HB-94 chemotherapy protocol was started at once due to rapid deterioration of the patient. Surgical biopsy performed after the first IPA (ifosfamide, cisplatin, doxorubicin) course showed hepatoblastoma with macrotrabecular variant. After a second IPA course and 2 courses of carboplatin and etoposide, the boy's clinical condition was excellent with normal alpha-fetoprotein but minimal regression and increased calcification in the tumor mass. Hepatic tumor was unresectable and no surgical intervention was performed. Transplantation could not be performed because of high morbidity and mortality. Despite general agreement that complete surgical resection is the cornerstone of treatment for patients with hepatoblastoma, the patient is in remission with 100% Karnofsky score in the 43 months of diagnosis.

Mesenchymal hamartomas of the liver: comparison of clinicopathologic features between cystic and solid forms

Mesenchymal hamartoma (MH) of the liver is an uncommon benign lesion related to ductal plate malformation. It is usually cystic and mainly composed of myxoid mesenchymal tissue with tortuous or cystic bile ducts. In order to characterize the clinicopathological features of MH, the Korean Gastrointestinal Pathology Study Group collected a total of 17 MH cases diagnosed in 7 hospitals from 1992 to 2002 and compared the clinicopathologic findings of cystic MH with those of solid variant. Among the 17 cases, 7 (41%) were solid. The solid form showed a higher serum level of alpha-fetoprotein (AFP), the smaller bile ducts, and more frequent proliferation of vessels. Serum AFP level was related to the amount of hepatocytes. Two of seven solid cases harbored a larger amount of evenly distributed hepatocytes and proliferation of small duct with focal hepatocyte-bile duct transition. These histologic findings are similar to those of mixed hamartoma. Therefore, the mixed hamartoma and the MH of both solid and cystic types could be the variants of one disease spectrum. And hepatocytes within MH might be rather a genuine tumor component than entrapped into the tumor. In conclusion, MH can show various clinicopathological features and recognition of these features will facilitate accurate diagnosis of MH.

Mesenchymal hamartoma of the liver: a systematic review

Mesenchymal hamartoma of the liver is the second commonest benign liver tumor in children, yet its biology and pathogenesis are poorly understood. Cytogenetic studies have suggested that the tumor may be a neoplasm rather than a hamartoma. Typically, it presents as a large benign multicystic liver mass in a child younger than 3 years amenable to complete resection. However, its imaging characteristics are variable, ranging from a few large cysts to a solid mass occupying one or both lobes of the liver. In addition, the tumor occasionally contains angiomatous elements or is multifocal. Most tumors gradually increase in size, some reaching enormous proportions, which can make surgery challenging. Paradoxically, a few undergo incomplete spontaneous regression and, on rare occasions, others have shown malignant transformation to undifferentiated (embryonal) sarcoma. These unusual pathological and biological features must be taken into account when considering the management of affected individuals.

[Hepatic tumors in childhood: experience on 245 tumors and review of literature]

This review on the pathology of hepatic tumors in childhood, from a personal series of 245 tumors, focuses on incidence, management, description of frequent tumors such as hepatoblastoma, fibrolamellar carcinoma, and undifferentiated sarcoma for malignant tumors, focal nodular hyperplasia, hepatocellular adenoma, and mesenchymal hamartoma for benign tumors. Malignant and benign entities of recent description, including the following: crowded, small cell undifferentiated and cholangioblastic variants of hepatoblastomas, mesenchymal hamartoma miming hepatoblastoma, liver adenoma and adenomatosis in diabete MODY3 families, gastrointestinal stromal tumor with liver metastasis associated to Carney triad, macronodules in non-cirrhotic portal fibrosis are reviewed. For each entity, the clinical presentation, the diagnostic criteria and the differential diagnosis are described. The role of immunohistochemistry and molecular biology in the diagnosis and identification of new molecular mechanisms triggered by oncogenic activation with new prognostic markers, and therapeutic targets is emphasized.